1. Field of the Invention
This invention relates to displacement measuring devices, and more particularly, it is concerned with improvements in a displacement measuring device suitable for use in a dial gauge, linear gauge, limit gauge or the like, wherein there is provided a measuring element slidably supported on a main frame and the length or the like of a work to be measured is measured from a displacement value of the measuring element when the forward end of the measuring element is abutted against the work to be measured.
2. Description of the Prior Art
Heretofore, there has been known a dial gauge or linear gauge wherein there is provided a measuring element slidably supported on a main frame and the length or the like of a work to be measured is measured from a displacement value when the forward end of the measuring element is abutted against the work to be measured, or a limit gauge wherein it is detected similarly from the displacement value of the measuring element whether the dimensions of the work to be measured are within a limit of allowance, for example, a tolerance.
In the displacement measuring devices of the type described, generally, in order to perform an accurate measurement, it is necessary to provide a load applying means for abutting the forward end of the measuring element against the work to be measured under a predetermined measuring load.
Furthermore, in order to facilitate repeated measurements of the works to be measured having dimensions identical with one another, it is necessary that, when the measuring element is abutted against the work to be measured under a predetermined measuring load, a measured value at this time is quickly detected and the measuring element can be quickly retracted and further advanced by a predetermined value from the state of abutment.
However, with the load applying means in the conventional displacement measuring devices, there have been such disadvantages that, for example, the load applying means is a spring to bias the measuring element in one direction, and a value of deformation of this spring is varied depending on a movement value of the measuring element, whereby uniform measuring load is not obtainable.
Further, the arrangement for performing a detection when the measuring element is abutted against the work to be measured under a measuring load beyond a predetermined value has been complicated, and consequently, has presented problems in construction and cost.